1. Field of the Invention
The present invention relates generally to a metal alloy, and in particular, to an alloy including palladium, boron and one or more additional elements as solutes, and in particular to an alloy of palladium, boron and at least one of ruthenium, rhenium, iridium, platinum, tungsten, gold, zirconium, cobalt, nickel and tantalum. In an alternative embodiment, the alloy is of palladium and at least one of ruthenium and rhenium with an additional element chosen from iridium, platinum, tungsten, boron, gold, zirconium, cobalt, nickel and tantalum. The invention also relates to a product formed of the foregoing alloys.
2. Description of the Related Art
Platinum alloys, in particular, platinum-iridium alloys have been used in a wide variety of applications. Platinum-iridium alloys are widely used for both disposable and implantable medical devices to fabricate radio opaque marker bands for catheters, electrode rings, platinum alloy wires and coils, tubes, and machined components.
For example, radio opaque platinum-iridium alloys are used during medical procedures involving fluoroscope imaging since the radio opaque platinum-iridium alloy shows up very clearly in the fluoroscope image to thereby aid the medical personnel in performing their tasks.
The platinum-iridium alloy can also have a high yield strength or hardness along with well-established biocompatibility, which permits it to be used in implantable medical devices, such as pacemakers. The high yield strength also allows for the use of very fine wires that can accept a high torque loading during the steering of catheters or guide wires through small diameter blood vessels. The higher strength wires allow for a reduction in the wire diameter without a fear of breakage during use. Smaller diameter wires allow for access into finer blood vessels.
Platinum-iridium alloys are also popular for use in jewelry manufacturing due to its excellent white color and good hardness as well as its ability to be used in sheet stock, wire goods and investment casting. Platinum-iridium alloys have a higher melting temperature than gold alloys but can be investment cast or fabricated by cold working, hot working, and annealing, or soldering
Another application is in space vehicle applications, thermocouples, electrical contacts, etc.
Platinum-iridium alloys are sold in varying proportions of platinum to iridium. For example, the common proportions are 90% platinum to 10%, iridium, referred to as 90:10 alloy, an alloy of 85% Pt-15% Ir, or 85:15, an alloy of 80% Pt to 20% Ir, or 80:20, an alloy of 75% Pt to 25% Ir, or 75:25, a 70:30 alloy, and even a 95:5 alloy.
In summary, platinum-iridium alloys are a mainstay in the medical market and are used for everything from guide wire tips and coils, due to the good radio opacity, to machined components and implantable pacemaker components. The jewelry trade uses the platinum-iridium alloys due to their combination of strength and resistance to tarnish and oxidation. The platinum-iridium alloys provide a combination of strength and biocompatibility.
However, the price of platinum has reached record levels, recently exceeding $900 per ounce, which is three times the current cost of palladium. This places significant economic strains on the continued use of high platinum alloys.